1// SPDX-License-Identifier: GPL-2.0+
2// Expose the Chromebook Pixel lightbar to userspace
3//
4// Copyright (C) 2014 Google, Inc.
5
6#include <linux/ctype.h>
7#include <linux/delay.h>
8#include <linux/device.h>
9#include <linux/fs.h>
10#include <linux/kobject.h>
11#include <linux/kstrtox.h>
12#include <linux/module.h>
13#include <linux/platform_data/cros_ec_commands.h>
14#include <linux/platform_data/cros_ec_proto.h>
15#include <linux/platform_device.h>
16#include <linux/sched.h>
17#include <linux/types.h>
18#include <linux/uaccess.h>
19#include <linux/slab.h>
20
21#define DRV_NAME "cros-ec-lightbar"
22
23/* Rate-limit the lightbar interface to prevent DoS. */
24static unsigned long lb_interval_jiffies = 50 * HZ / 1000;
25
26/*
27 * Whether or not we have given userspace control of the lightbar.
28 * If this is true, we won't do anything during suspend/resume.
29 */
30static bool userspace_control;
31
32static ssize_t interval_msec_show(struct device *dev,
33 struct device_attribute *attr, char *buf)
34{
35 unsigned long msec = lb_interval_jiffies * 1000 / HZ;
36
37 return sysfs_emit(buf, fmt: "%lu\n", msec);
38}
39
40static ssize_t interval_msec_store(struct device *dev,
41 struct device_attribute *attr,
42 const char *buf, size_t count)
43{
44 unsigned long msec;
45
46 if (kstrtoul(s: buf, base: 0, res: &msec))
47 return -EINVAL;
48
49 lb_interval_jiffies = msec * HZ / 1000;
50
51 return count;
52}
53
54static DEFINE_MUTEX(lb_mutex);
55/* Return 0 if able to throttle correctly, error otherwise */
56static int lb_throttle(void)
57{
58 static unsigned long last_access;
59 unsigned long now, next_timeslot;
60 long delay;
61 int ret = 0;
62
63 mutex_lock(&lb_mutex);
64
65 now = jiffies;
66 next_timeslot = last_access + lb_interval_jiffies;
67
68 if (time_before(now, next_timeslot)) {
69 delay = (long)(next_timeslot) - (long)now;
70 set_current_state(TASK_INTERRUPTIBLE);
71 if (schedule_timeout(timeout: delay) > 0) {
72 /* interrupted - just abort */
73 ret = -EINTR;
74 goto out;
75 }
76 now = jiffies;
77 }
78
79 last_access = now;
80out:
81 mutex_unlock(lock: &lb_mutex);
82
83 return ret;
84}
85
86static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
87{
88 struct cros_ec_command *msg;
89 int len;
90
91 len = max(sizeof(struct ec_params_lightbar),
92 sizeof(struct ec_response_lightbar));
93
94 msg = kmalloc(size: sizeof(*msg) + len, GFP_KERNEL);
95 if (!msg)
96 return NULL;
97
98 msg->version = 0;
99 msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
100 msg->outsize = sizeof(struct ec_params_lightbar);
101 msg->insize = sizeof(struct ec_response_lightbar);
102
103 return msg;
104}
105
106static int get_lightbar_version(struct cros_ec_dev *ec,
107 uint32_t *ver_ptr, uint32_t *flg_ptr)
108{
109 struct ec_params_lightbar *param;
110 struct ec_response_lightbar *resp;
111 struct cros_ec_command *msg;
112 int ret;
113
114 msg = alloc_lightbar_cmd_msg(ec);
115 if (!msg)
116 return 0;
117
118 param = (struct ec_params_lightbar *)msg->data;
119 param->cmd = LIGHTBAR_CMD_VERSION;
120 msg->outsize = sizeof(param->cmd);
121 msg->result = sizeof(resp->version);
122 ret = cros_ec_cmd_xfer_status(ec_dev: ec->ec_dev, msg);
123 if (ret < 0 && ret != -EINVAL) {
124 ret = 0;
125 goto exit;
126 }
127
128 switch (msg->result) {
129 case EC_RES_INVALID_PARAM:
130 /* Pixel had no version command. */
131 if (ver_ptr)
132 *ver_ptr = 0;
133 if (flg_ptr)
134 *flg_ptr = 0;
135 ret = 1;
136 goto exit;
137
138 case EC_RES_SUCCESS:
139 resp = (struct ec_response_lightbar *)msg->data;
140
141 /* Future devices w/lightbars should implement this command */
142 if (ver_ptr)
143 *ver_ptr = resp->version.num;
144 if (flg_ptr)
145 *flg_ptr = resp->version.flags;
146 ret = 1;
147 goto exit;
148 }
149
150 /* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
151 ret = 0;
152exit:
153 kfree(objp: msg);
154 return ret;
155}
156
157static ssize_t version_show(struct device *dev,
158 struct device_attribute *attr, char *buf)
159{
160 uint32_t version = 0, flags = 0;
161 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
162 int ret;
163
164 ret = lb_throttle();
165 if (ret)
166 return ret;
167
168 /* This should always succeed, because we check during init. */
169 if (!get_lightbar_version(ec, ver_ptr: &version, flg_ptr: &flags))
170 return -EIO;
171
172 return sysfs_emit(buf, fmt: "%d %d\n", version, flags);
173}
174
175static ssize_t brightness_store(struct device *dev,
176 struct device_attribute *attr,
177 const char *buf, size_t count)
178{
179 struct ec_params_lightbar *param;
180 struct cros_ec_command *msg;
181 int ret;
182 unsigned int val;
183 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
184
185 if (kstrtouint(s: buf, base: 0, res: &val))
186 return -EINVAL;
187
188 msg = alloc_lightbar_cmd_msg(ec);
189 if (!msg)
190 return -ENOMEM;
191
192 param = (struct ec_params_lightbar *)msg->data;
193 param->cmd = LIGHTBAR_CMD_SET_BRIGHTNESS;
194 param->set_brightness.num = val;
195 ret = lb_throttle();
196 if (ret)
197 goto exit;
198
199 ret = cros_ec_cmd_xfer_status(ec_dev: ec->ec_dev, msg);
200 if (ret < 0)
201 goto exit;
202
203 ret = count;
204exit:
205 kfree(objp: msg);
206 return ret;
207}
208
209
210/*
211 * We expect numbers, and we'll keep reading until we find them, skipping over
212 * any whitespace (sysfs guarantees that the input is null-terminated). Every
213 * four numbers are sent to the lightbar as <LED,R,G,B>. We fail at the first
214 * parsing error, if we don't parse any numbers, or if we have numbers left
215 * over.
216 */
217static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr,
218 const char *buf, size_t count)
219{
220 struct ec_params_lightbar *param;
221 struct cros_ec_command *msg;
222 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
223 unsigned int val[4];
224 int ret, i = 0, j = 0, ok = 0;
225
226 msg = alloc_lightbar_cmd_msg(ec);
227 if (!msg)
228 return -ENOMEM;
229
230 do {
231 /* Skip any whitespace */
232 while (*buf && isspace(*buf))
233 buf++;
234
235 if (!*buf)
236 break;
237
238 ret = sscanf(buf, "%i", &val[i++]);
239 if (ret == 0)
240 goto exit;
241
242 if (i == 4) {
243 param = (struct ec_params_lightbar *)msg->data;
244 param->cmd = LIGHTBAR_CMD_SET_RGB;
245 param->set_rgb.led = val[0];
246 param->set_rgb.red = val[1];
247 param->set_rgb.green = val[2];
248 param->set_rgb.blue = val[3];
249 /*
250 * Throttle only the first of every four transactions,
251 * so that the user can update all four LEDs at once.
252 */
253 if ((j++ % 4) == 0) {
254 ret = lb_throttle();
255 if (ret)
256 goto exit;
257 }
258
259 ret = cros_ec_cmd_xfer_status(ec_dev: ec->ec_dev, msg);
260 if (ret < 0)
261 goto exit;
262
263 i = 0;
264 ok = 1;
265 }
266
267 /* Skip over the number we just read */
268 while (*buf && !isspace(*buf))
269 buf++;
270
271 } while (*buf);
272
273exit:
274 kfree(objp: msg);
275 return (ok && i == 0) ? count : -EINVAL;
276}
277
278static char const *seqname[] = {
279 "ERROR", "S5", "S3", "S0", "S5S3", "S3S0",
280 "S0S3", "S3S5", "STOP", "RUN", "KONAMI",
281 "TAP", "PROGRAM",
282};
283
284static ssize_t sequence_show(struct device *dev,
285 struct device_attribute *attr, char *buf)
286{
287 struct ec_params_lightbar *param;
288 struct ec_response_lightbar *resp;
289 struct cros_ec_command *msg;
290 int ret;
291 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
292
293 msg = alloc_lightbar_cmd_msg(ec);
294 if (!msg)
295 return -ENOMEM;
296
297 param = (struct ec_params_lightbar *)msg->data;
298 param->cmd = LIGHTBAR_CMD_GET_SEQ;
299 ret = lb_throttle();
300 if (ret)
301 goto exit;
302
303 ret = cros_ec_cmd_xfer_status(ec_dev: ec->ec_dev, msg);
304 if (ret < 0) {
305 ret = sysfs_emit(buf, fmt: "XFER / EC ERROR %d / %d\n", ret, msg->result);
306 goto exit;
307 }
308
309 resp = (struct ec_response_lightbar *)msg->data;
310 if (resp->get_seq.num >= ARRAY_SIZE(seqname))
311 ret = sysfs_emit(buf, fmt: "%d\n", resp->get_seq.num);
312 else
313 ret = sysfs_emit(buf, fmt: "%s\n", seqname[resp->get_seq.num]);
314
315exit:
316 kfree(objp: msg);
317 return ret;
318}
319
320static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
321{
322 struct ec_params_lightbar *param;
323 struct cros_ec_command *msg;
324 int ret;
325
326 msg = alloc_lightbar_cmd_msg(ec);
327 if (!msg)
328 return -ENOMEM;
329
330 param = (struct ec_params_lightbar *)msg->data;
331 param->cmd = cmd;
332
333 ret = lb_throttle();
334 if (ret)
335 goto error;
336
337 ret = cros_ec_cmd_xfer_status(ec_dev: ec->ec_dev, msg);
338 if (ret < 0)
339 goto error;
340
341 ret = 0;
342error:
343 kfree(objp: msg);
344
345 return ret;
346}
347
348static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
349{
350 struct ec_params_lightbar *param;
351 struct cros_ec_command *msg;
352 int ret;
353
354 msg = alloc_lightbar_cmd_msg(ec);
355 if (!msg)
356 return -ENOMEM;
357
358 param = (struct ec_params_lightbar *)msg->data;
359
360 param->cmd = LIGHTBAR_CMD_MANUAL_SUSPEND_CTRL;
361 param->manual_suspend_ctrl.enable = enable;
362
363 ret = lb_throttle();
364 if (ret)
365 goto error;
366
367 ret = cros_ec_cmd_xfer_status(ec_dev: ec->ec_dev, msg);
368 if (ret < 0)
369 goto error;
370
371 ret = 0;
372error:
373 kfree(objp: msg);
374
375 return ret;
376}
377
378static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
379 const char *buf, size_t count)
380{
381 struct ec_params_lightbar *param;
382 struct cros_ec_command *msg;
383 unsigned int num;
384 int ret, len;
385 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
386
387 for (len = 0; len < count; len++)
388 if (!isalnum(buf[len]))
389 break;
390
391 for (num = 0; num < ARRAY_SIZE(seqname); num++)
392 if (!strncasecmp(s1: seqname[num], s2: buf, n: len))
393 break;
394
395 if (num >= ARRAY_SIZE(seqname)) {
396 ret = kstrtouint(s: buf, base: 0, res: &num);
397 if (ret)
398 return ret;
399 }
400
401 msg = alloc_lightbar_cmd_msg(ec);
402 if (!msg)
403 return -ENOMEM;
404
405 param = (struct ec_params_lightbar *)msg->data;
406 param->cmd = LIGHTBAR_CMD_SEQ;
407 param->seq.num = num;
408 ret = lb_throttle();
409 if (ret)
410 goto exit;
411
412 ret = cros_ec_cmd_xfer_status(ec_dev: ec->ec_dev, msg);
413 if (ret < 0)
414 goto exit;
415
416 ret = count;
417exit:
418 kfree(objp: msg);
419 return ret;
420}
421
422static ssize_t program_store(struct device *dev, struct device_attribute *attr,
423 const char *buf, size_t count)
424{
425 int extra_bytes, max_size, ret;
426 struct ec_params_lightbar *param;
427 struct cros_ec_command *msg;
428 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
429
430 /*
431 * We might need to reject the program for size reasons. The EC
432 * enforces a maximum program size, but we also don't want to try
433 * and send a program that is too big for the protocol. In order
434 * to ensure the latter, we also need to ensure we have extra bytes
435 * to represent the rest of the packet.
436 */
437 extra_bytes = sizeof(*param) - sizeof(param->set_program.data);
438 max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes);
439 if (count > max_size) {
440 dev_err(dev, "Program is %u bytes, too long to send (max: %u)",
441 (unsigned int)count, max_size);
442
443 return -EINVAL;
444 }
445
446 msg = alloc_lightbar_cmd_msg(ec);
447 if (!msg)
448 return -ENOMEM;
449
450 ret = lb_throttle();
451 if (ret)
452 goto exit;
453
454 dev_info(dev, "Copying %zu byte program to EC", count);
455
456 param = (struct ec_params_lightbar *)msg->data;
457 param->cmd = LIGHTBAR_CMD_SET_PROGRAM;
458
459 param->set_program.size = count;
460 memcpy(param->set_program.data, buf, count);
461
462 /*
463 * We need to set the message size manually or else it will use
464 * EC_LB_PROG_LEN. This might be too long, and the program
465 * is unlikely to use all of the space.
466 */
467 msg->outsize = count + extra_bytes;
468
469 ret = cros_ec_cmd_xfer_status(ec_dev: ec->ec_dev, msg);
470 if (ret < 0)
471 goto exit;
472
473 ret = count;
474exit:
475 kfree(objp: msg);
476
477 return ret;
478}
479
480static ssize_t userspace_control_show(struct device *dev,
481 struct device_attribute *attr,
482 char *buf)
483{
484 return sysfs_emit(buf, fmt: "%d\n", userspace_control);
485}
486
487static ssize_t userspace_control_store(struct device *dev,
488 struct device_attribute *attr,
489 const char *buf,
490 size_t count)
491{
492 bool enable;
493 int ret;
494
495 ret = kstrtobool(s: buf, res: &enable);
496 if (ret < 0)
497 return ret;
498
499 userspace_control = enable;
500
501 return count;
502}
503
504/* Module initialization */
505
506static DEVICE_ATTR_RW(interval_msec);
507static DEVICE_ATTR_RO(version);
508static DEVICE_ATTR_WO(brightness);
509static DEVICE_ATTR_WO(led_rgb);
510static DEVICE_ATTR_RW(sequence);
511static DEVICE_ATTR_WO(program);
512static DEVICE_ATTR_RW(userspace_control);
513
514static struct attribute *__lb_cmds_attrs[] = {
515 &dev_attr_interval_msec.attr,
516 &dev_attr_version.attr,
517 &dev_attr_brightness.attr,
518 &dev_attr_led_rgb.attr,
519 &dev_attr_sequence.attr,
520 &dev_attr_program.attr,
521 &dev_attr_userspace_control.attr,
522 NULL,
523};
524
525static const struct attribute_group cros_ec_lightbar_attr_group = {
526 .name = "lightbar",
527 .attrs = __lb_cmds_attrs,
528};
529
530static int cros_ec_lightbar_probe(struct platform_device *pd)
531{
532 struct cros_ec_dev *ec_dev = dev_get_drvdata(dev: pd->dev.parent);
533 struct cros_ec_platform *pdata = dev_get_platdata(dev: ec_dev->dev);
534 struct device *dev = &pd->dev;
535 int ret;
536
537 /*
538 * Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC
539 * devices like 'cros_pd' doesn't have a lightbar.
540 */
541 if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0)
542 return -ENODEV;
543
544 /*
545 * Ask then for the lightbar version, if it's 0 then the 'cros_ec'
546 * doesn't have a lightbar.
547 */
548 if (!get_lightbar_version(ec: ec_dev, NULL, NULL))
549 return -ENODEV;
550
551 /* Take control of the lightbar from the EC. */
552 lb_manual_suspend_ctrl(ec: ec_dev, enable: 1);
553
554 ret = sysfs_create_group(kobj: &ec_dev->class_dev.kobj,
555 grp: &cros_ec_lightbar_attr_group);
556 if (ret < 0)
557 dev_err(dev, "failed to create %s attributes. err=%d\n",
558 cros_ec_lightbar_attr_group.name, ret);
559
560 return ret;
561}
562
563static void cros_ec_lightbar_remove(struct platform_device *pd)
564{
565 struct cros_ec_dev *ec_dev = dev_get_drvdata(dev: pd->dev.parent);
566
567 sysfs_remove_group(kobj: &ec_dev->class_dev.kobj,
568 grp: &cros_ec_lightbar_attr_group);
569
570 /* Let the EC take over the lightbar again. */
571 lb_manual_suspend_ctrl(ec: ec_dev, enable: 0);
572}
573
574static int __maybe_unused cros_ec_lightbar_resume(struct device *dev)
575{
576 struct cros_ec_dev *ec_dev = dev_get_drvdata(dev: dev->parent);
577
578 if (userspace_control)
579 return 0;
580
581 return lb_send_empty_cmd(ec: ec_dev, cmd: LIGHTBAR_CMD_RESUME);
582}
583
584static int __maybe_unused cros_ec_lightbar_suspend(struct device *dev)
585{
586 struct cros_ec_dev *ec_dev = dev_get_drvdata(dev: dev->parent);
587
588 if (userspace_control)
589 return 0;
590
591 return lb_send_empty_cmd(ec: ec_dev, cmd: LIGHTBAR_CMD_SUSPEND);
592}
593
594static SIMPLE_DEV_PM_OPS(cros_ec_lightbar_pm_ops,
595 cros_ec_lightbar_suspend, cros_ec_lightbar_resume);
596
597static struct platform_driver cros_ec_lightbar_driver = {
598 .driver = {
599 .name = DRV_NAME,
600 .pm = &cros_ec_lightbar_pm_ops,
601 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
602 },
603 .probe = cros_ec_lightbar_probe,
604 .remove_new = cros_ec_lightbar_remove,
605};
606
607module_platform_driver(cros_ec_lightbar_driver);
608
609MODULE_LICENSE("GPL");
610MODULE_DESCRIPTION("Expose the Chromebook Pixel's lightbar to userspace");
611MODULE_ALIAS("platform:" DRV_NAME);
612

source code of linux/drivers/platform/chrome/cros_ec_lightbar.c